Roper Dryer - heating without drum rotation

[tsitalon1]

Hey guys,

I need some help, I own a Roper electric dryer that is only a few years old and has worked flawlessly up until this point.

I am going to do my best to keep this post short and direct.


Initial issue:

No heat while running


initial repair:

Replace heating element


Circumstances:

While I have been around electronics and consider myself very versed in the use of multimeters. I mad mistake that almost proved deadly. During the "no heat" troubleshooting, I decided to test for presence of 240v at the heating element. I was very careful not to touch anything except the elements terminals, however, I failed to notice that my multimeter was in resistance mode. This of course resulted in a very large boom (as the meter blew up in my hand) and it also tripped the meter.

After I sat on the couch for 30 minutes to examine my life , I unplug the dryer and test for resistance at the heating element and I found an open circuit. I then replaced the element.

At this point the dryer was geting hot even with the timer in the off position. I guessed that the short (that I created while testing) probably damaged the timer. I opened the timer and found that the terminals BL and R were welded together from the previous short. I was able to break the weld and file the contacts back smooth again. I tested the timer contacts as described in the manual and all connections seem proper.

New problem:

When the timer is set to any running/heating cycle, the heating element will engage even though the start button wasn't depressed or the drum rotating. I tested the start button and it was good. I tested for shorts at the drive motor/switch for a shorted connection and found none. I also notice the timer motor seems louder and seems to wanna continue turning even in the off position. I would appreciate any/all help/suggestions.

Things I've tested:

Timer contacts - work as described on the schematic (while timer out of dryer)

Drive motor/switch - no short as found testing on switch contacts with dryer and wire harness disconnected.

Start button - not shorted, works normally


I have attached a copy of my schematic for your review.

Thanks for any/all help again,
James

[JWWebster]

Let me get this straight: you turn the timer the heater element comes on now? Does the drum turn?

[tsitalon1]

That is correct. I turn the timer to a heating cycle, the element comes on. ( I haven't pushed the start switch yet) the drum doesn't turn until AFTER I push the start button.

[Mr. Fix-It]

I've seen this before it was the centrifugal switch on the motor stuck in the on position.

[tsitalon1]

That is what I thought...however testing the switch (without power) shows open circuits, I'm a little nevous to test with power on though

[Mr. Fix-It]

Did you test across the 2 red wires on the motor?

[Repair-man]

The element likely has a direct short. Test it with a new OHM meter...this time unplug the dryer first

If the coil on the element is touching metal, it will heat. You might find a bra wire or something there as well. Touching either teminal of the element and any metal surface on the dryer will show a short.

[tsitalon1]

Yep, tested across both red wires, no connection with dryer unplugged...didn't try with dryer plugged in.

I don't think it's a shorted heating element as the element was replaced after my initial mistake... I'll check for a short though...it should show 7-8-11ohms if the schematic is right, and no connectivity at all from either side of the element to chassis ground right?

[Repair-man]

If you pull the wires off and test the terminals of the element, look for about 14 OHMs.

The only way the thing can heat is if there is 240 volts at the terminals or if the coil is grounded. Of course, I am assuming you wired it correctly and did not get confused by the thermal limit wires.

[tsitalon1]

Repair-man,

You hit it right on the nose. I measured 11ohms on the two element contacts. Then I measured 5 ohms from either contact to chassis ground. I found the element wire itself contacting the metal enclosure thus allowing 120v to power the element.

Problem resolved!!!!!

I owe you a 12-pack a beer! Pm me your paypal addy and beer is on me tonight! Thanks!!

James

[Repair-man]

See the little beer icon under my username? That's how you buy me a beer. Glad you resolved the problem!

[tsitalon1]

You have beer!

Thanks again.